Food Structure


A Cream cheese was made by mixing cultured high fat cream (5~% fat) with Queso Blanco curd and by homogenizing the mix at 70°C. The final product contained 30. 01. to 33.)% fat and 54.1 to 54.5% moisture. The Queso Blanco curd was obtained by precipitating the casein and denatured whey protein from heated whole milk (b2.~ to SI8.0°C) by bringing the pH to 5.3-5.5 with citric acid, using a continuous process. The extent of denaturation of the whey protein portion varied from 5 to 100%, depending on the heat treatment of the milk. Scanning and transmission electron microscopy revealed the development of microstructure at individual manufacturing stages.

A characteristic core-and-lining ultrastructure of the casein matrix was observed in the Queso Blanco curd, the nature of which depended on the temperature of coagulation. Nixing of the curd with the cultured cream in a Polytron blender dispersed the curd into particles approximately 50 j.J m in diameter. Subsequent homogenization at l7.2J MPa \i.e ., 2,50U psi or 170 atm) further reduced the dimensions of both the protein (<7 j.J m in diameter) and fat (<) J.Jm in diameter) particles and produced a unifonn microstructure.

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